The invention relates to a sound absorber having a bottom portion and a structure portion, there being formed, in the structure portion, hollow chambers which have chamber walls and which are formed like small boxes or cups, and the bottom portion furthermore being joined to the structure portion, for example welded thereto, and the hollow chambers being open on one side.
An absorber of this kind is known, for example, from DE-OS 27 58 041. In the known absorber, the hollow chambers of the structure portion are covered by a planar film as the bottom portion, which film seals air-tight each of the air volumes contained in the individual hollow chambers. Furthermore, there is known, from DE-OS 40 11 705, a further embodiment of a sound absorber of this kind, in which the structure portion is joined only at the edge to the bottom portion. The joiner is provided here by means of an elastic sealing lip. The sound absorber may be manufactured as a whole in this manner by the blow moulding method. Embodiments are also known in which each hollow chamber is joined to the bottom portion, each such hollow chamber, open at the top, being formed however as a Helmholtz resonator. In a sound absorber known from DE-PS 32 33 654, there are likewise formed individual, separate hollow chambers which, however, have at the top side a structuring in the form of a groove.
Moreover, with regard to the state of the art, reference is further made to DE-OS 40 35 177, DE-PS 42 41 518 and DE-GM 92 15 132.